<style>
    div{
        text-align: center;
    }
</style>
<?php
echo "<div >";
echo "<h3>abs函数：求绝对值　</h3>";
$num=-1;
echo abs($num);
echo "<h3>ceil函数：进一法取整　</h3>";
$num=1.1;
echo ceil($num);
echo "<h3>floor函数：舍去法取整　</h3>";
$num=1.1;
echo floor($num);

echo "<h3>round：对浮点数进行四舍五入运算　</h3>";
$num=1.6;
echo round($num);

echo "<h3>max函数：找出最大值　</h3>";

echo max('1','2','9');

echo "<h3>min函数：找出最小值　　</h3>";

echo min('1','2','9');

echo "<h3>rand函数：产生一个随机整数　</h3>";
for ($i=0;$i<10;$i++){
    echo rand(0,10);
    echo ",";
}

echo "<h3>time函数：返回当前的UNIX时间戳　</h3>";
echo time();
echo "<h3>date 函数：格式化一个本地时间/日期</h3>";
echo date("Y-m-d h:i:s");
echo "<h3>strtotime函数：将任何英文文本的日期、时间描述解析为UNIX时间戳　</h3>";
$dtime=date("Y-m-d h:i:s");
echo strtotime($dtime);

echo "<h3>define函数：定义一个常量的值　</h3>";
define("APP_NAME","PHP");
echo APP_NAME;

echo "<h3>defined函数：判断一个常量是否存在　</h3>";
echo defined("APP_NAME");

echo "<h3>die函数：退出程序　</h3>";
//die;

echo "<h3>eval函数：将一个字符串作为PHP代码来执行　</h3>";
$s="echo APP_NAME;";
eval($s);

echo "<h3>exit函数：退出并输出信息　</h3>";
//exit("退出并输出信息　");

echo "<h3>sleep函数：暂停执行程序　</h3>";
//sleep(1);


echo "<h3>\$_SERVER</h3>";
//var_dump($_SERVER);
echo $_SERVER['HTTP_ACCEPT'];
echo "<br>";
echo $_SERVER['REMOTE_ADDR'];
echo "<br>";
echo $_SERVER['DOCUMENT_URI'];
echo "<h3>\$_REQUEST</h3>";
print_r($_REQUEST);
echo "<h3>\$_POST</h3>";
print_r($_POST);
echo "<h3>\$_GET</h3>";
print_r($_GET);











echo "</div>";




